Massively multiplayer online role-playing game (MMORPG) is a genre of role-playing video games or web browser-based games in which a very large number of players interact with one another within a virtual game world. As in all RPGs, players assume the role of a character (often in a fantasy world or science-fiction world) and take control over many of that character's actions. MMORPGs are distinguished from single-player or small multi-player online RPGs by the number of players, and by the game's persistent world, which continues to exist and evolve while the player is offline and away from the game.